Gas-producing nondetonating composition



Patented July 22, 1 952 l Gas-PRODUCING NONDETONAT ING oomosrrroN 1 7 James Taylor and Alexander CantlayHutchison, Saltcoats, Scotland, assignors to Imperial Chemical Industries Limited, a corporation of Great Britain No Drawing". Application June'24, 1949,'Serial In Great Britain November 8,

'5 Claims. (c1. 52-

The present invention relates to new or improved gas-producing charges of the kind capable of propagating-a self-sustained gas-producmg non-detonating decomposition throughout themselves, when they are locally heated'by a limited non-detonating ignitin g'elementg that is to say, one capable of heating a small" portion of the charge to a high temperature and insufficient of itself to effect any substantial general rise in the temperature of'the charge. r

Depending on the rate at which the gas-producing decomposition is propagated throughout the charge under increasing pressure conditions, the nature of the gases produced, the amount and, quality of any solidproducts of the reaction and the presence: or absence of flame, such chargesfind applicationifor a variety of pur'-'- poses, mcludingyfor instance, the generation of gas pressure for actuating pneumatically oper ated mechanical devices and blasting operations when a slow heaving action is winning of lump coal. 7

This application is a continuation-impart of applicants copendi'ng application" Serial 'No. 774,693, filed September 17 1947,-now abandoned.

It isknown in the art that and nitroguanidine' may be decomposed when strongly heated, giving a good yield of permanent gases that would be suitable for the aforesaid purposes leaving acertain amount of solid residue.

U. S. Patent No. 2,159,234, discloses a composition which may be usedas a non 'detonating, gas generating compositio capable of undergoing a self-sustaining decomposition" without detona tion. This composition comprises at least one substance selected from the groupconsisting of ammonium nitrate, guanidine nitrate, 'urea ni trate and dicyandiamidine nitrate; a carbonaceous material; and from 1 to 20% of asensitizing agent comprising at least'o'ne member, of the group'consisting of chromic oxide, alkali metal. chromates, ammonium chromate, ammonium d i.-,

chromate and alkali metal polychromates. If. a cooling salt is included inthe composition, the

composition may be employedf or bl gti' pur a suitable proportion of a chromate or bichro-' mate, the decomposition oiacharge of the mixture whichhas not previously been heatedy will sustain itself throughout 'the entire charge. once it has been excited by temporary heating of a required, as in the guanidine nitrate local portion of the charge as by means of a limited heating element such as an electric powder fuse or a red hot rod even at ordinary pressure.

The composition taught in U. S. Patent No. 2,159,234 which could consist of guanidine nitrate, a carbonaceous material, and from 1 to 20% of a chromate or dichromate has the disadvantage that it requires a relatively large amount of the chromate or dichromate in order to produce a composition which will burn at a high rate and still produce a gas under low pressure. The'inclusion ofa high percentage of a chrothata large amount of residue remains after ignition of the composition. If, for example, such a composition were utilized for thermally vaporizing a pesticidal compound, unburned ash resulting from the presence of the chromate or dichromate would exist and could be clearly objectionable. Furthermore, the use of a chromate or dichromate sensitizer with guanidine nitrate does not produce a composition having a sufiiciently high burning rate to vaporize, for example, a pesticidal compound in a short time as might be required in fumigating open areas in the field. If the pesticide in this case were not vaporized quickly, .it should be evident that the pestlcidal compound would be dispersed by the wind or other elements prior to the time that a sufficient concentration of the vaporized pesticide could be built up to accomplish its purpose. Other uses for which higher burning rates at increased pressures might be required have necessitated further research by the applicants. It is the result of this research that has brought the present invention into being.

An object of the present invention, therefore,-

is the provision ofimproved charges for gas pressure operated devices which charges include compositions capable of undergoing a self-sustained, gas-producing, non-detonating decomposition when ignited with the aid of a local-and limited heating element.

A further object of the present invention is to produce a charge of the aforesaid characteristics whichhas a relatively high burning rate com- 1 pared with those compositions previously produced by the teaching of the prior art.

Another object of this invention is to produce a composition which is not only of a higher relative'burning rate but which also, upon decomposition, evolves a higher yield of permanent gases than would be possible upon the decomposition 3 of the prior arts compositions and which evolve this higher yield of gases without leaving a large amount of residue as do the compositions of the prior art.

Further objects of this invention will become apparent upon consideration of the description of the invention hereinafter.

Applicants have found that copper powder and copper compounds in pulverulent condition act as sensitizers for the thermal decomposition of nitroguanidine and guanidine nitrate, thereby enabling the production of new or-improved charges suitable for the aforesaid purpose-and capable of decomposing with the evolution ofa high yield of permanent gases at a higher rate of evolution even at low pressures without leaving a residue of objectionable unburnt componentsof thesiensitizers.

According to the present invention, therefore, a

gas-producing charge of the kind suitable for carrying out the objects of this invention comprises a composition of which the-preponderating constituent is at least one nitrogen containing compound selected from the group consisting of nitroguanidine and guanidine nitrate and inadmixture with said compound acoppercontaining pulverulent sensitizer for thethermal decompositionof said compound selected from the group consisting of copperpowder, cupric oxide, cupro-us chloride and cuprous oxylate. Other copper compounds-may be utilizedbut-preferablythose which arenon-hygroscopic"arethe ones preferred in this invention. In certain instances, when cuprous chloride is used as a sensitizing agent, a slight amount of chlorine is evolved. In-engine driving, for example, this is obj ectionableand copper oxide is preferablyemployed instead of cuprous chloride-asa sensitizing agent.

I Certain compounds of vanadium may desirably be utilized along with cuprous chloride for the purpose or further increasing the rate 1 of burning'of the'composition. Vanadium pentoxide in an amoun-t of 1% =Whe'n' added 'to mixtures of guanidi'ne nitrate or nitroguanidine sensitized by cup'r'ous chloride 'caus'es a marked increase in the rate of burning. 1

Charges made in accordance with -:this invention decomposesmoot'hly when they are ignited, and'in compressed condition,they do not undergo discontinuous volume changes at -temper'atures at'which -they are likel'y to be exposedon' storage. It is further possible, according to the invention,

- to obtain charges that decompose without flame when they are locally heated 'an'dwhich' are,'-accordingly, suitable for blasting in fiery. or i dusty mines. For blasting purposes, it is frequently de sirable to co'nfine th'e :niixtnre :in order "to enable the pressure :to be builtiup satisfactorilyiandifor this purpose, a blasting assembly comprising a gas producing charge confined in apressurei-resisting vessel thavingithe :clo'sure adapted. to yield ata.predeterminedzpressure .mayconveniently be employed.

- The invention. is illustrated in the "following examples in which the parts ;arei:parts 'by weight of the total composition.

4 burst a disc V inch thickness. An electric powder fuse containing 60 grains of black powder is used to excite the decomposition.

Example 12 A mixture consisting of 97 parts of guanidine nitrate and 3 parts of cuprous chloride was prepared by milling the powder in a ball mill until .anintimate mixture was obtained. A quantity of this mixture was pressed in the form of a pellet 'in a hydraulic press.

The sensitized charge so formed was found to be capable of decomposition in a self-sustained manner when ignited by the application ofheat and it had a burning rate of 0.038 inch per second at a pressure of 125 pounds per square inch.

ture consisted of 90 parts f guanidine nitrate and 10 .parts of ammonium dichromate-inade up in the form of ExampleZ. W hen ignited by the application of heat, .it'had aburning rate of only 0.028 inch per second at a pressule of approximately loolpoundspersquare inch.

Example .4

2.0 partsof cuprous. chloride and 80 partsof guanidine :nltrate are mixed together in a mechanical mortar. 200 grams. ofthis mix-ture when decomposed in a steel tube :blastingdevice 3 feet long by -l%izinchestinternal diameter bursts adisc inch thickness. An :electric :powder fuse containing thirty-grains black'powder is used to excite the decomposition.

It is noted-that in this example, a; much higher percentage of cuprous chloride is present as a sensitizer for guanidine'nitrate than inExample l. The bursting power for a disc in the two examples is thesame. However, in Example 1, the preferred ratio of cuprous-chloride to guanidine nitrate is employed 'andas a result, relatively no residue is presentafter decomposition ofthe mixture in Example 1 as compared with .the

, residue present upon decomposition of the composition of this: example.

Whereas it has been indicated that bothmitroguanidine and guanidine nitrate may be sensitized by a small amount of .a copper-containing compound. there-are advantages in particular instancesin usingnitroguanidine in preference-to guanidine nitrate and inother instances innsing guanidine nitrate in '-preference to nitroguani- 'dine, Guanidine nitrate is cheaper than nitro-' guanidine, it is non-explosive, and has better pressing properties. However, .nitroguanidine compositions are relatively non-hygroscopic in comparison with 'guanidine nitrate compositions. Also, nitroguanidine sensitized compositions generally produce ,hotter gases than the guanidine nitrate compositions. If, therefore, .itis desirable to'have a composition relatively less hygroscopic or if it is desired to have a composition which produces hotter gases, nitroguanidine is the preferred compound to be sensitized. In all .other cases, considering cost, non-explosive qualities and better pressing properties, it is more desirable to use guanidine nitrate.

We claim:

'1. A gas-producing charge of the type herein defined consisting essentially of at least one nitrogen-containing compound selected from the group consisting of nitroguanidine and guanidine nitrate and 2 to 20% by weight of a pulverulent copper-containing sensitizer selected from the group consisting of copper, cupric oxide, cuprous chloride, and cuprous oxylate.

2. A gas-producing charge as set forth in claim 1 wherein the sensitizer comprises cuprous chloride.

3. A gas-producing charge of the type herein defined consisting essentially of at least one nitrogen-containing compound selected from the group consisting of nitroguanidine and guanidine nitrate; 2 to 20% by weight of a pulverulent copper-containing sensitizer selected from the group consisting of copper, cupric oxide, cuprous chloride, and cuprous oxylate; and a small percentage of vanadium pentoxide.

4. A gas-producing charge as set forth in claim 3 wherein the sensitizer comprises cuprous ch10- ride and the vanadium pentoxide is present in proportion of 1% by weight.

5. A gas-producing charge of the type herein defined consisting essentially of guanidine nitrate and 2 to 20% by weight of a pulverulent coppercontaining sensitizer selected from the group consisting of copper, cupric oxide, cuprous chloride, and cuprous oxylate.

JAMES TAYLOR. ALEXANDER CANTLAY HUTCHISON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,159,234 Taylor May 23, 1939 V FOREIGN PATENTS 20 Number Country Date 21,189 Great Britain 1902 

1. A GAS-PRODUCING CHARGE OF THE TYPE HEREIN DEFINED CONSISTING ESSENTIALLY OF AT LEAST ONE NITROGEN-CONTAINING COMPOUND SELECTED FROM THE GROUP CONSISTING OF NITROGUANIDINE AND GUANIDINE NITRATE AND 2 TO 20% BY WEIGHT OF A PULVERULENT COPPER-CONTAINING SENSITIZER SELECTED FROM THE GROUP CONSISTING OF COPPER, CUPRIC OXIDE, CUPROUS CHLORIDE, AND CUPROUS OXYLATE. 